Forming fabrics

Abstract

A papermaker's fabric for use as a forming fabric. The fabric may include bondable or meltable monofilament yarns which may be formed from materials that retain substantial strength and tenacity after thermal treatment. Further, the remaining yarns in the forming fabric may be formed from materials that have a higher melting temperature than the monofilament material that will be thermally bonded or melted.

1. A papermaker's fabric comprising:
 a first layer having a plurality of machine direction (MD) yarns and cross-machine direction (CD) yarns; 
 a second layer having a plurality of MD yarns and CD yarns; and 
 a third layer of CD yarns;
 wherein a plurality of machine direction (MD) yarns bind said CD yarns of the first, second, and third layers; 
 wherein said MD yarns and said CD yarns in said first layer and said second layer are monofilament yarns, and said CD yarns of said third layer are monofilament yarns; 
 wherein at least some of said CD yarns of said first, second and third layers are in a vertically stacked relationship with each other, and have a first melting point temperature, and the MD yarns have one or more melting point temperatures each higher than said first melting point temperature; and 
 wherein said fabric is heated to a predetermined temperature which is at least equal to said first melting point temperature yet lower than each of said one or more melting point temperatures of the MD yarns; and 
 wherein the at least some of said CD yarns of said first, second, and third layers, which are in contact with each other or in close proximity to each other prior to being heated, bond with each other after being heated to said predetermined temperature. 
 
 
     
     
       2. The papermaker's fabric according to  claim 1 , wherein said MD yarns of said first layer and said MD yarns of said second layer have a first diameter and said CD yarns of said first layer and said CD yarns of said second layer have one or more diameters each equal to or larger than said first diameter. 
     
     
       3. The papermaker's fabric according to  claim 1 , wherein said yarns of said group are formed from MXD6. 
     
     
       4. The papermaker's fabric according to  claim 3 , wherein said MD yarns of said first layer and said MD yarns of said second layer are formed from polyethylene naphthalate (PEN) or polyethylene terephthalate (PET). 
     
     
       5. The papermaker's fabric according to  claim 3 , wherein said first melting point temperature has a value in the range of approximately 230° C. to 234° C., and wherein said fabric is heated for a predetermined time which is in the range of approximately 60 to 180 seconds. 
     
     
       6. The papermaker's fabric according to  claim 5 , wherein the yarns are placed in tension having a value in the range of approximately 0.07 to 0.25 cN/dtex when said fabric is heated. 
     
     
       7. The papermaker's fabric according to  claim 1 , wherein said fabric does not contain binder yarns. 
     
     
       8. The papermaker's fabric according to  claim 1 , wherein adjacent ones of said CD yarns in said first, second and third layers which are in contact with each other or in close proximity to each other prior to being heated, bond with each other after being heated to said predetermined temperature. 
     
     
       9. The papermaker's fabric according to  claim 8 , wherein said CD yarns of said first, second and third layers are formed from MXD6. 
     
     
       10. The papermaker's fabric according to  claim 9 , wherein said first melting point temperature has a value in the range of approximately 230° C. to 234° C., and wherein said fabric is heated for a predetermined time which is in the range of approximately 60 to 180 seconds. 
     
     
       11. The papermaker's fabric according to  claim 10 , wherein the yarns are placed in tension having a value in the range of approximately 0.07 to 0.25 cN/dtex when said fabric is heated. 
     
     
       12. The papermaker's fabric according to  claim 8 , wherein said CD yarns of said first, second and third layers which are in contact with or in close proximity to said MD yarns prior to being heated fuse with said MD yarns after being heated to the predetermined temperature. 
     
     
       13. A method of manufacturing a papermaker's fabric comprising the steps of:
 weaving a first layer having a plurality of machine direction (MD) yarns and cross-machine direction (CD) yarns; 
 weaving a second layer having a plurality of MD yarns and CD yarns; 
 weaving a third layer of cross machine direction (CD) yarns such that a plurality of machine direction (MD) yarns bind said CD yarns of the first, second and third layers;
 wherein said MD yarns and said CD yarns in said first layer and said second layer are monofilament yarns, and said CD yarns of said third layer are monofilament yarns; 
 wherein at least some of said CD yarns of said first, second and third layers are in a vertically stacked relationship with each other, and have a first melting point temperature, and the MD yarns have one or more melting point temperatures each higher than said first melting point temperature; and 
 
 heating said fabric to a predetermined temperature which is at least equal to said first melting point temperature yet lower than each of said one or more melting point temperatures of the remaining yarns; and
 wherein the at least some of said CD yarns of said first, second, and third layers, which are in contact with each other or in close proximity to each other prior to being heated, bond with each other after being heated to said predetermined temperature. 
 
 
     
     
       14. A papermaker's fabric for use as a forming fabric comprising:
 a first layer having a plurality of machine direction (MD) yarns and cross-machine direction (CD) yarns; and 
 a second layer having a plurality of MD yarns and CD yarns;
 wherein said MD yarns and said CD yarns in said first layer and said second layer are monofilament yarns; 
 wherein a group including at least some of said CD yarns of said first layer and at least some of said CD yarns of said second layer have a first melting point temperature and the remaining yarns have one or more melting point temperatures each higher than said first melting point temperature; 
 wherein said fabric is heated to a predetermined temperature which is at least equal to said first melting point temperature yet lower than each of said one or more melting point temperatures of the remaining yarns; and 
 wherein the CD yarns of said first layer of said group and said CD yarns of said second layer of said group which are in contact with each other or in close proximity to each other prior to being heated, bond with each other after being heated to said predetermined temperature, wherein said yarns of said group are formed from MXD6. 
 
 
     
     
       15. A method of manufacturing a papermaker's fabric for use as a forming fabric comprising the steps of:
 weaving a first layer having a plurality of machine direction (MD) yarns and cross-machine direction (CD) yarns; 
 weaving a second layer having a plurality of MD yarns and CD yarns;
 wherein said MD yarns and said CD yarns in said first layer and said second layer are monofilament yarns; 
 wherein a group including at least some of said CD yarns of said first layer and at least some of said CD yarns of said second layer have a first melting point temperature and the remaining yarns have one or more melting point temperatures each higher than said first melting point temperature; and 
 
 heating said fabric to a predetermined temperature which is at least equal to said first melting point temperature yet lower than each of said one or more melting point temperatures of the remaining yarns;
 wherein said CD yarns of said first layer of said group and said CD yarns of said second layer of said group which are in contact with each other or in close proximity to each other prior to being heated, bond with each other after being heated to said predetermined temperature, wherein said yarns of said group are formed from MXD6.